Install volt meter in place of ammeter wiring question

I did dive into my wiring harness and do several changes at once. For many owners it will likely be better to do one thing at a time. Stay on the amp meter to volt meter until complete. If you do anything, do it right. The volt meter should get a decent input signal from that dark blue w/ white. Voltage drop in the ignition switch , etc.. is possible but lets not go there yet.
Attaching the ground side of the volt meter to just anywhere on the instrument cluster is not efficient. Buy some wire and route that ground signal to a true chssis ground. A sheet metal screw with toothed washer behind the left kick panel is one option but
all the way to the battery ground terminal would be the very best. A 10 amp fuse in that wire is a good idea also since the only fuse in the positive side is the fusible link. You dont want a failed aftermarket gauge or chaffed wire to kill the whole car.
My inline fuses are behind the column cover and labelled so I know whats what. The volt meter inline fuse is in the blue w/ white. This explains why I ask others to sell pieces of wiring harnesses to me.